I have previously posted on the internal lengthening nail. Just recently a technique article I authored was published in Orthopedics Today, and is now available on the web too. Interestingly, it is published in the pediatrics section. Most surgeons who do deformity correction are indeed pediatric orthopaedists (or at least do quite a bit of pediatric work). And I believe the fastest growing segment for these lengthening nails is in adolescents (one could argue thats a gray area between pediatric and adult orthopaedics). However, I think that my fellowship training was unique in that although I did get some exposure to pediatric cases, the majority of my experience is in adult deformity correction.
This nail works great for adults, and is it not uncommon to see adults of all ages with limb length discrepancies. Some from trauma or infection, but many with congenital discrepancies that were never addressed because limb lengthening was more burdensome for the patient in the past. Anyway, without further ado, here is the technique paper, its a quick read with some nice pictures.